As a part of a general survey on leishmaniases and sandflies of the Maltese islands, 22 Leishmania stocks were isolated from human visceral (1) and cutaneous (1) cases, dogs (16) and sandflies (4). They were characterized by the analysis of 15 enzymes. The commonest Mediterranean L. infantum zymodeme, MON 1, was found to cause human and canine visceral leishmaniasis; L. infantum MON 78, which has so far been isolated only in Malta, was the agent of human cutaneous leishmaniasis. Both zymodemes were isolated from the same sandfly species, Phlebotomus perniciosus.